story, a Chicago police officer convicted of murder in the shooting of a teenager, officer Jason Van Dyke now facing years behind bars. ABC’s Alex Perez is in Chicago with what jurors are saying about this big decision. Alex, good morning. Reporter: Good morning, whit. The anticipation for this verdict started when that police dash cam video was released three years ago, the jury working quickly delivering their decision in less than ten hours. Demonstrators filling the streets of Chicago in celebration following the verdict and the racially charged case surrounding Chicago police officer Jason Van Dyke. The jury taking less than ten hours to reach their decision. We the jury find the defendant, Jason Van Dyke, guilty. Reporter: Van Dyke showing little emotion as jurors found him guilty of second degree murder and 16 counts of aggravated battery, one for each shot in the 2014 killing of 17-year-old laquan McDonald. He going to jail. Reporter: Just outside the courtroom, jubilation as the verdict was handed down. McDonald’s family saying justice was served. Laquan McDonald represents all of the victims that suffered what he suffered across the country. Reporter: Months’ long protest began when the infamous dash cam video was released showing the white officer shooting the black teenager as he walked down a Chicago street carrying a three-inch knife. On the witness stand Van Dyke who was responding to a call of someone breaking into cars testified he believed McDonald was lunging at him and refused commands to drop the knife. I was yelling at him, drop the knife. I yelled it I don’t know how many times. Reporter: But in the video McDonald who was high on pcp appears to be walking away from Van Dyke when he is shot. There’s no justification for shooting laquan McDonald that night. Not one shot, not the first shot, not the 16th shot. Reporter: But defense attorneys arguing the video was, quote, essentially meaningless because it didn’t capture the incident from Van Dyke’s point of view. But the jury confident in their ruling. He should have realized what the situation was and instead of escalating the situation should have at least looked at other options. We didn’t come here because of race or — we came here for right and wrong. Reporter: Van Dyke could possibly face decades behind bars. Those protests remained peaceful. Eva. Thank you, Alex.

This transcript has been automatically generated and may not be 100% accurate.